Plastic-coated metallic foams

ABSTRACT

The properties of articles fabricated from foamed metals (such as foamed aluminum) are enhanced by coating surfaces thereof with plastic materials, e.g. acrylonitrile-butadiene-styrene polymers. For example, the plastic coating improves the physical properties, and enables the article to be joined to another foamed metal article, or to a metal sheet, wire, glass, rock or other material. The organic coat gives improved strength to such joint.

United States Patent [72] Inventors ChesterP.Jarema Detroit; Leonard M.Niebylski, Birmingham, both of Mich. [21] Appl. No. 774,756 [22] FiledNov. 12, 1968 [45] Patented Nov. 2, 1971 [73] Assignee Ethyl CorporationNew York, N.Y.

[54] PLASTIC-COATED METALLIC FOAMS Claims, 1 Drawing Fig.

[52] U.S.C1 ll7/l32B, 117/132 BE, 1 17/132 BF, 117/132 BS, 117/132 [51]Int. Cl B32b /08 Field ofSearch /20; 117/99, 132, 161, 126 GR,75,5.3;161/213; 260/] [56] References Cited UNITED STATES PATENTS2,076,295 4/1937 Curs et a1 106/22 Primary Examiner-William D. MartinAssistant Examiner-Harry J. Gwinnell Attorney-Donald L. JohnsonABSTRACT: The properties of articles fabricated from foamed metals (suchas foamed aluminum) are enhanced by coating surfaces thereof withplastic materials, e.g. acrylonitrile-butadiene-styrene polymers. Forexample, the plastic coating improves the physical properties, andenables the article to be joined to another foamed metal article, or toa metal sheet, wire, glass, rock or other material. The organic coatgives improved strength to such joint.

PATENTED'NM ism v 3517.364

l PLASTIC-COATED'METALLIC FOAMS BACKGROUND OF THE INVENTION Foamedmetals have been described in the prior art, see, for

example, U.S. Pat. Nos. 2,895,819, 3,300,296, and 3,297,431.

SUMMARY OF THE INVENTION It has been discovered that foamed metalbodiesproduced by methods-such as generally described and referred to abovearematerially enhanced by coating them with a plastic material.

For example, the coating adds strength, especially insuch cases wherethe coating is imbibed into the surface of the metal by filling thecavities on the surface. (Such cavities can be relatively large tomicroscopic in size.) Second, such coatings can provide a means forattaching a foamed metal to another body. This is done by melting theplastic coating, pressing it to the surface to be attached so the moltenplastic sticks to both surfaces to be bonded, and then cooling.Furthermore, the coating can be decorative. Moreover, the surface can bealtered to confer different properties by a proper choice of the coatingpolymer. Thus, to make a more or less slippery surface, a film of Tefloncan be fused on the surface of the foamed body. To make the body elasticor springy," a rubber can be fused thereon. To make the surface sticky,an adhesive can be used. The adhesive layer can be covered forprotection prior to use by a sheet of paper, cloth or the like.

In addition, the plasticcoating can markedly improve other properties.Thus, coated plastics of this invention haveless tendency to absorbliquids such as water. Compressive, flexural, shear, and tensilestrengths are improved; friability is decreased.

The FIGURE, which is not to scale, illustratesthis invention. In theFIGURE, ABCD represents a section through a foamed metal body, saidsection being taken by cuts along AB,

BD, and CD. The circles and partial circles within ABCE represent crosssections of bubbles in the foamed substrate. The bubbles were made byblowing gas during the foaming process. As can be seen, these bubblescan be of equal or different sizes, wholly separated, or joinedtogether. It is not necessary that the bubbles be spherical as shown.

As illustrated, there are three cavities in Surface AC of the foamedsubstrate (in the illustrated section). Of course, these cavities can beformed during the blowing process and the number of cavities can be moreor less in any given section.

ACFE represents a layer of plastic on Surface AC of the foamedsubstrate. As illustrated, the plastic layer extends into the cavitiesin the coated surface. This invention covers surfaces having cavitieswhich are partially filled, substantially filled, or entirely tilled.

DESCRIPTION OF PREFERRED EMBODIMENTS The plastics which can be used tocoat-foamed metals according to this invention can be chosen from a widevariety of materials.

The following illustrative but nonlimiting outline serves to demonstratewhat types of plastics can be used in polymercoated foamed metalsprovided by this invention.

A. Derivatives of Natural Products Cellulose nitrate, cellulose acetate,cellulose acetatebutyrate, ethyl-cellulose, rubber, vulcanized rubber,chlorinated rubber. B. Phenolic Materials Bakelite, phenol-formaldehydenovolacs and resoles, A-

stage, B-stage, and C-stage resins.

C. Other Formaldehyde-based Polymers Condensation products offormaldehyde with urea or melamine.

D. Alkyd Resins Condensation products of alcohols such as glycerine,ethylene glycol, diethylene I glycol or pentaerythritol with succinic,adipic, citric, sebacic, azelaic, phtlialic, terephthalic, or maleicacid.

E. Epoxides and Phenoxy Resins Alkaline condensation product ofepichlorohydren with bisphenol A. I

F. Silicones G. Furan Polymers Polymers of furfuryl alcohol orfurfural,'furfural-phenolics, urea-fomaldehyde resins containingfurfuryl alcohol.

H. Nylons Condensation products of diacids with diamines.

I. Polyaniides Nylon-6 J. Polyurethanes Reaction products oftoluene-2,4-diisocyanate and polyhydric alcohols K. Thiokols L.Polycarbonates Produced by phosgenation of dihydroxy aromatics such asbisphenol A.

M. Polysulfones Reaction products of bisphenol A and bis-(p-chlorophenyl)sulfone.

N. Chlorinated Polyester I Produced by polymerizing 3,3-bis(chloromethyl)l-oxacyclobutane in liquid SO with BF 0. Acetal PolymersDelrin, Celcon P. Polyphenylene Oxide Q. Polyimides Produced bycondensation of dianhydrides such as pyromellitic anhydride andpolyamines such as 4,4- diaminodiphenyl ether.

R. Polyxylenes and Polyoxyethylenes S. Polyolefins Polyethylene,polypropylene, isotactic poly-I-butene, copolymers of ethylene and vinylacetate, methyl acreylate, propylene, and acrylic acid.

T. Polystyrene U. Vinyl Polymers Polyvinyl chloride, polymers ofunsaturated esters such as methyl methacrylate, allyl esters, ethylmethacrylate,

vinyl acetate. Copolymers of vinyl chloride and vinylidene chloride,polyvinyl acetals.

V. Fluorinated Ethylene-propylene, Tetrafluoroethylene and RelatedFluorinated Materials W. Poly (alkyl vinyl ethers), Polycarbazole, andPolyvinylpyrollidones.

The plastic or polymeric coating agent(s) need not be pure but in manyinstances are advantageously admixed with other materials. Thus,stabilizers, antioxidants, antiozonants, dyes, fillers, antistaticagents, antitack and slip agents, Bacteriostats, b'righteners, flameretardants, U.V. absorbers, and plasticizers can be used in the plasticor polymeric coats. For example of such materials known in the art onecan refer to tables in I968 edition of Modern Plastics Encyclopedia,McGraw Hill Inc., New York, N.Y. Such tables (in that publication) asthose beginning on are incorporated by reference herein as if fully setforth. In addition, the plastic'can be mixed with other substances suchas silicon carbide, ground glass, or similar substance to render thecoating layer abrasive or nonskidding.

The organopolymers can be employed singly or in combination. When usedin combination, two, three, four or more of the above types of resinscan be variously combined. For example, the coat can be a more or lesshomogeneous mixture of plastics or two or more plastics can be added tothe foamed body in successive layers. Thus, laminar coats are anembodiment of the invention.

For example, the use of successive coats can form bodies having improvedproperties and/or bodies having acceptable properties at lower costs.Thus, the foamed metal can be first treated with a resinuous materialwhich seeps into the cavities on the surface. More particularly, thisfirst coat can, for example, be applied as a liquid, such as a solutionof a polymer in an organic solvent. Afterwards, the solvent-whichfacilitates seepage into the pores of the metal foam-is then allowed toevaporate, leaving the polymer coat on the foam. Alternatively, thefirst treatment can be with a monomer (or solution, emulsion, orsuspension thereof) followed by polymerization of the monomer on (and inthe surface cavities) of the foam. If the monomer is applied togetherwith an organic solvent, the solvent can be removed either before orafter the polymerization, as desired. Monomers and polymers can be addedby spraying, dipping or rolling.

Continuing the building of a laminar coat, other layers of the same ordifferent polymeric materials can be overlayed on the first coat.

ln addition to polymeric materials, other types of substances can beoverlayed on the first layer.

Thus, for example, one or more layers of a plastic, such as aphenol-formaldehyde resin, can be applied to a foamed aluminum sheet.Next, a sheet of aluminum foil is bonded to the plastic coating, andthen (optionally) overlayed with another layer of plastic. Next, a paperis bonded to the articlewhich paper optionally has a decorative designon the upward surface. The paper is then coated with a transparent,resistant plastic coat which protects the paper design from H,O, air,etc. The resultant foamed sheet is useful as a building panel sandvvichwherein the foamed aluminum portion provides lightweight, structuralstrength and the coated paper surface yields an aesthetically pleasingdecorative effect. Such sandwich composite can be used for interior orvouter walls.

The layers of materials built up on a coated, foamed metal body of thisinvention need not be wholly integral. For example, such layers built upon the coated surface can be a plastic foam. The coated surface providesa better bond between the foamed plastic and the foamed metal.

Thus, for example, a relatively flat surface of a foamed metal sheet iscoated with a polymeric coat which is imbibed into the foam surface andforms a relatively smooth surface on the foamed body. This is thenoverlayed with a tacky overcoat of adhesive material so that theadhesive surface is exposed.

Next, (temporary, if desired) sides are provided around the metal sheetso said sheet forms with the sides, an open boxlike structure with theadhesive surface being exposed in the box. (ln other words, the bottomof the boxlike structure is the foamed metal sheet.) Then, a foamableplastic composition is placed on the adhesive surface to the desireddepth, the sides serving to confine the foamable composition so there isminimal spillage. Thereafter, the plastic composition is allowed to foamand the adhesive surface provides a bond between the plastic and metalfoams. The plastic foam can be flexible, rigid, or semirigid as desired.

These composite plastic and metal foams have many desirable utilities.Thus, they can be used in the walls of vehicular compartments. When soused, the metal foam is outside while the plastic foam is on the inside.With such configuration, the metal foam can pick up much shock shouldthere be an impact. The plastic foam on the inside has more give thanthe metal foam, and it better protects freight or passengersinadvertently jostled against the compartment walls during impact.

Moreover, composite plastic metal foams can be used as flooring. in thisinstance, the foamed metal provides structural strength. The plasticfoam adherent thereon is a built-in pad for carpeting. If desired, theplastic foam surface can have the carpeting prebonded thereto, and/or,noncoated surfaces of the metal foam body can have tongues and grooves(or some other surface configuration) provided to facilitate laying.

Of course, more than one surface of the metal foam can have a plasticfoam bonded thereto. Thus, for example, opposing surfaces can beprovided with an adherent plastic foam to form a sandwichlike structure.

Illustrative but nonlimiting plastic foams which can be bonded to ametal foam according to this invention are polystyrene (expanded beads),polyurethanes, and vinyl-containing foams such as described in Alzner etal. and Klopfer, U.S. Pat. Nos. 3,338,845, and 3,338,846, respectively.

As illustrated above, polymeric coast applied to foamed metals accordingto this invention can be used as bonding agents to bond other materialsto a foamed metal article. According to one embodiment of thisinvention, the material so bonded need not provide a uniform surface.Thus, for example, a polymeric coat which is meltable can be applied toa surface of the foamed metal article. This can then be melted to form atacky surface. Into this, crushed rock can be embedded and the surfacethen cooled to form a foamed metal article having an irregular surfaceprovided by the crushed rock coat. These articles provide a new artisticmedium. Moreover, by varying the colors of the crushed rock, foamedmetal sheets can provide an extremely eyepleasing wall unit. As desired,the color pattern of such curtain walls can be chosen to provide acheckerboard, variegated, mosaic, or combined effect.

Curtain walls and other structural units made from plasticcoated metalfoams according to this invention need not have surfaces unaffected byatmospheric or environmental conditions. In fact, this inventionencompasses embodiments where changes due to the environment are usedadvantageously. Thus, one embodiment of this invention comprises afoamed metal structural unit having a plastic coating thereon containinga phosphorescent or fluorescent material. Such structural units glow inthe dark after being exposed to light or fluoresce. Compounds such aacridine dyes, Rhodamine B and Rhodamine 60 as well as other materialsdiscussed in Kirk- Othmer's Encyclopedia of Chemical Technology, 2ndEdition, (in the section under Luminescent Materials") can be used.

in addition, electrically conducted wires can be embedded into theplastic layer attached to the foamed substrate. This provides a curtainwall panel which can be used to heat a room by radiant heat whenelectric current is called to flow through the resistance wires.

Similarly, materials which change color upon exposure to differentamounts of moisture can be stuck in the plastic coat and exposed to theenvironment. Salts such as cobaltous chloride and bromide can be used inthis manner.

A plastic layer can be applied to the foamed metal body by cold molding.According to this technique, an organic composition is admixed with aphenolic resin dispersed in a solvent. This is admixed with a fillersuch as asbestos fibers, silica, or magnesia. The resultant mass, wherepossible, is preshaped to the approximate shape of the finished article.Next, the composition and the foamed metal body is put into a mold. Thecomposition and foamed metal substrate is then pressed together underpressure to bond the polymeric-containing material to the foamed metalsubstrate. There is no heating or cooling cycle.

Alternatively a plastic layer can be applied by hot-compression molding.This technique is best employed for thermosetting compositions, becausethermoplastic materials require cooling before removal of the articleand preheating before receiving the next charge. This adds to expensebecause of the time lost.

In general, the charge and the foamed metal substrate are placed in aheated mold, the mold is closed, generally under low pressure, untilpressure is exerted on the material. The charge becomes plastic andunder increased pressure is forced to fill cavities in the surface ofthe foam substrate. The molded article is Ikept under pressure untilcured. After that, the mold is opened and the molded part removed.

The charge is usually beads, scraps, granules, or it may be tableted orpreformed. Preforming is advantageous when flow is poor, such as withpolytetrafluorethylene.

The charge can be preheated prior to insertion in the mold. Electronic,steam, and air preheating are art-recognized methods. Molding is usuallycarried out at l45-380 C. More preferably, temperatures from M5-200 C.are used. The pressure utilized can be from, say, 300-800 p.s.i.g.;usually it is best to use pressures from 500-5000 p.s.i.g. Low pressurescan be used while the mold is being closed and higher temperatures canbe used during molding.

Transfer molding techniques such as those described on pages 587-589 ofGolding, Polymers and Resins, D. Van Nostrand Co., Inc. New York (1959)can be used.

All types of foamed materials can be used as substrates for thisinvention. However, a highly preferred embodiment is plastic-coatedfoamed aluminum. The aluminum can be alloyed with various metals. Thus,it can contain up to about 50 percent of magnesium, manganese, orcopper. Foamed aluminum containing up to about weight percent lead alloytherewith is a preferred embodiment because such foamed aluminums havesuperior sound-dampening properties.

The following alloys yield foams suitable for this invention when usedin a process employing a titanium or zirconium hydride as a blowingagent. Suitable techniques are the processes of the prior art set forthin the patents cited herein in the section Background of the Invention".Moreover, said alloys yield suitable foams when the molten alloy is mademore viscous by a suitable viscosity-increasing agent.

Alcoa alloy Alcoa alloy 7075-( 1.6% Cu, 2.5% Mg, 0.3% Cr, 5.6% Zn,remainder Al) 2024(4.5% Cu, 0.6% Mn, 1.5% Mg, remainder Al) 5086(0.45%Mn, 4.0% Mg, 0.1% Cr, remainder Al) 6063-(0.4% Si, 0.7% Mg, remainderAl) Almag 35 (6-8% Mg, in Al) 1000 series A1 (99.6% minimum A1) 201l-(5.5% Cu, 0.5% Pb, 0.5% Bi, remainder Al) 2218(4.0% Cu, 1.5% Mg, 2Ni,remainder A1) 3005( 1.2% Mln, 0.4% Mg, remainder A1) 4042( 12.2% Si,0.9% Cu, 1.1% Mg, 0.9% Ni, remainder Al) 4043-(5% Si, 95% A1) 8280( 1.5%Si, 1.0% Cu, 0.5% Ni, remainder Al) Magnalium-70% Al, 30% Mg) EXAMPLE 1The following is a general procedure illustrating preparation ofplastic-coated metal foams by a hot-compression-molding technique.

A sample of a foamed aluminum having a density of 10-40 percent of thedensity of aluminum ingot is employed. Such samples have approximatedimensions of 6X2 1 inches. At least one of the 6X2 inches surfaces ischaracterized by having a pitted" configuration. Such pittedconfiguration can be gained by preparing the sample by making a sectionthrough a foamed aluminum body of said density wherein the pore sizeaverages one-sixteenth-three thirty-seconds of an inch and the pore sizeof, say, 80 percent of the pores range from about one-eighth to aboutone sixty-fourth.

From 5-15 g. of Acrylonitrile-butadiene-styrene resin is placed on the6X2 inches surface above described. (A resin used was Tybrene 27,Natural 7 supplied by Dow Chemical Co. Such plastic is a solid inpellitized form.) Where desired,

the pellets are admixed with approximately 2 percent by weight of a dye.Dyes found suitable are the following, supplied by Allied Chemical Corp.

BC 70920-plasto blue G BC 7092l-plasto blue RDA BC 70922-plasto green BBC 70923-plasto orange R BC 70924-plasto red B BC 70925-plasto yellowMGS BC 70926-plasto yellow Y The foamed metal substrate, plastic (anddye) are placed in a hydraulic press whose 6X6 inches platens havepreviously been heated to 475-500 F. The material is so placed in thepress that the plastic (and dye) is on top. Between the top platen andthe pellets is placed a covering sheet of a somewhat heavy gaugealuminum foil, say, l5-mil thick. The press is barely closed, say, toabout 50 pounds per square foot and allowed to remain in thisconfiguration for about 3-5 minutes. In this manner the hot top platenheats the plastic.

Thereafter, additional pressure can be applied, say, an additional 10-50pounds per square foot, to cause the plastic to melt and flow over theentire top surface of the foamed aluminum. when the entire top surfaceis covered with the plastic, the plastic-coated foam is removed from thepress. This yields a plastic-coated foam to which is attached the heavyfoil.

This object is then cooled, optionally with water or other coolant suchas dry ice. The aluminum foil can be removed, if desired.

Using about 5 g. of resin on the surface above described, yields acoated foam having a thin coat of plastic thereon. In other words, thetops of the walls of the pore surfaces are visible through the plastic.This gives an aesthetically pleasing effect similar to a cloisonne, withmost of coat embedded into the surface cavities of the foam filling themup to make a smooth surface. Of course, more plastic than 5 g. yields athicker coat on the surface of the metal foam.

The process described above lends itself well to scale-up. Thus, largercoated foamed bodies can be made to order if comparatively largeramounts of plastic (and dye) are employed between larger platens onbigger samples of substrate.

The above procedure has been extended to a thermosetting melamine resin.The platen temperature was 375 F. About 5 g. of undyed melamine resinwas used and the resultant plastic-coated foam surface was white-grayhaving a marblelike appearance.

Similarly, the above procedure was applied to a methacrylate resin whichhad been admixed with a hardener. A clear plastic coat was obtained.

Similarly, a polypropylene coat was laid down using a platen temperatureof 400 F.

In the cases wherethe above technique was employed, the polymericmaterial had filled cavities in the treated surface.

Utilizing the low pressures employed in this example, coated materialswere made from other samples of foamed aluminum in which the cavitieswere larger than those mentioned above. In one instance, the cavities,in general were from three thirty-seconds-five thirty-seconds inch insize. Utilizing this material a commeusurately greater amount of plasticwas employed.

In instances where the above general procedure was employed, visualinspection demonstrates that the cavities in the surface so treated arewell filled with plastic material to depths of the cavities present inthe surface.

For much smaller cavities, it is expedient to increase the compressionand/or temperature pressure to force the plastic to flow into thesmallerpores. Pressures in the range of 10-200 p.s.i.g. areadvantageously employed. Usually, it is preferred to use a pressure lessthan that which compresses the foamed substrate, but higher pressurescan be employed if desired to materially alter the treated surface byadmixing the plastic coat with a crushed-foamed surface.

A liquid polyester resin (Michigan Fibreglas Sales, Inc. No. 130) wasadmixed with a hardener (Michigan Fibreglas Sales, Inc. EH No. 37) inthe ratio of four parts resin to one part hardener. This was then spreadupon a foamed aluminum sample having a pore size of from aboutone-sixteenth to about one thirty-second as described in example I.(Brushing, rolling, or spraying are suitable application techniques.)After application, a fiber glass mat was placed on the resin surface andthe resin allowed to harden. After drying, another coat of resin wasapplied to the top of the fiber glass. This was allowed to dry and wassanded. Additional layers of resin and fiber glass can be applied beforeor after sanding.

EXAMPLE 3 This example gives an illustrative general procedure forpreparing a plastic-coated metal foam having items embedded in theplastic layer.

Foamed aluminum samples are prepared as in example I, utilizing 5-15 g.of ABS resin on a 6X2 inches foamed metal surface.

Thereafter the coated material (coated side up) is put back in the presswhich has the platens preheated to a temperature which will soften theplastic coat. A suitable platen temperature is 475500 F.

After the plastic-coated material is softened, a material to be embeddedin the plastic coat is placed on the softened surface. lllustrativesubstances are quartz, marble, or enamel chips, crushed rock, metalflakes, wires, or tumings and glass wool, or beads. Pressure of 10-100pounds per square foot is then impressed, forcing the substance to embedin the coat. Pressure is released and the resultant object allowed tocool.

Using the above procedure, two foamed aluminum bodies can be joined byplacing one body into a softened coat on another body. In this way,plastic is between the butted surfaces. Foamed aluminum bodies can alsobe joined using plastic coats on top, bottom, and/or sides of bothconjoined bodes with plastic between or not present between the buttedsurfaces as desired.

EXAMPLE 4 Some foamed metal samples have a large number of open cellsand/or small imperfections in the walls of apparently closed cells.These allow fluid to penetrate freely from surface cavities into thebody of the foamed metal. Utilizing such samples, plastic coats can beapplied which penetrate to any desired depth in the foamed body.

This is illustrated by the following procedure. A mixture of Polyclear,an acrylic substance supplied by Transene Co. Inc. of Rowley,Massachusetts, is mixed with a hardener as directed by the supplier. Ifthis mixture is immediately applied to foamed aluminum having smallimperfections in the cell walls, the quite fluid mixture will penetrateto about 70 percent of the depth of a 1-inch thick foam beforehardening. Alternatively, if the mixture is allowed to set up for aboutl5 minutes before application, the penetration is lessened by 20-30percent.

If the mixture is allowed to set up for longer periods, the penetrationcan be further lessened.

Carvable epoxy coats can be made from slurn'es of epoxy resins coated onfoamed metals. The epoxy-foam composite can be used for tooling needssuch as for numerical control cutting machines.

We claim:

1. As an article of manufacture, a foamed metal body having a surfacethereof coated with a relatively thin layer of organopolymeric plasticcoating.

2. An article of claim 1 wherein said organopolymeric plastic coating atthe interface of said coating and said foamed metal body has penetratedinto cavities in said surface of said bod 3. An article of claim 1wherein said organopolymeric plastic coating consists substantially ofan acrylonitn'le-butadiene-styrene resin.

4. An article of Claim 1 wherein said foamed metal body is foamedaluminum.

5. An article of claim 4 wherein said foamed aluminum has a density ofabout 10 percent by weight of that of cast aluminum.

6. An article of claim 5 wherein said foamed aluminum is an alloy having6-8 weight percent magnesium.

7. An article of claim 6 wherein said foamed aluminum has an averagepore size of from about one thirty-second to about three thirty-secondsof an inch.

8. An article of claim 7 having a surface coated withacrylonitrile-butadiene-styrene resin.

9. An article of claim 7 having a surface coated with a resin that is, acondensation product of formaldehyde and melamine.

10. An article of claim 7 coated with a fiber glass reinforced polyesterresin.

i t i Q mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent5 617 36 1 Dated Nnvpmhp'r' 9 10?"! Inventor) fhaai-Qr D Z' at 2.1

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 96, "ABCE" should read ABCD Column line 20 coast" shouldread coats Column 5, line 39 Alcoa alloy should be deleted as it appearstwice Column 5, line i-9, "ENi" should read 2 Ni Column 5, line Fl, inch("1: should be inserted after /6 Signed and sealed this 2nd day of May 1972.

( SllkIJ Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSGHALK Attesting Officer Commissionerof Patents

2. An article of claim 1 wherein said organopolymeric plastic coating atthe interface of said coating and said foamed metal body has penetratedinto cavities in said surface of said body.
 3. An article of claim 1wherein said organopolymeric plastic coating consists substantially ofan acrylonitrile-butadiene-styrene resin.
 4. An article of Claim 1wherein said foamed metal body is foamed aluminum.
 5. An article ofclaim 4 wherein said foamed aluminum has a density of about 10 percentby weight of that of cast aluminum.
 6. An article of claim 5 whereinsaid foamed aluminum is an alloy having 6-8 weight percent magnesium. 7.An article of claim 6 wherein said foamed aluminum has an average poresize of from about one thirty-second to about three thirty-seconds of aninch.
 8. An article of claim 7 having a surface coated withacrylonitrile-butadiene-styrene resin.
 9. An article of claim 7 having asurface coated with a resin that is, a condensation product offormaldehyde and melamine.
 10. An article of claim 7 coated with a fiberglass reinforced polyester resin.